Peristaltic hose pump

ABSTRACT

The invention relates to a peristaltic hose pump comprising a roller wheel ( 1 ), which can rotate about a roller wheel axis D and which has rollers ( 2 ) that are mounted on the roller wheel ( 1 ). The rollers ( 2 ) roll away on a circular path having a radius R1 with regard to the roller wheel rotation axis D. The peristaltic hose pump also comprises a pressure arched element ( 3 ) with a supporting surface ( 4 ), whereby the supporting surface ( 4 ) extends along a circular path having a radius R2 around the rotation axis D of the roller wheel ( 1 ). In addition, a flexible hose ( 19 ) can be placed between the supporting surface ( 4 ) and the rollers ( 2 ) of the roller wheel ( 1 ). According to the invention, the supporting surface (4) is formed out of an elastically deformable synthetic material, and the pressure arched element ( 3 ) is pre-shaped with the provision that the extension of the supporting surface ( 4 ), when the pressure arched element ( 3 ) is not under tension, essentially corresponds to the extension of the supporting surface ( 4 ) when under tension.

SCOPE OF THE INVENTION

[0001] The invention relates to a peristaltic hose pump comprising aroller wheel, which can rotate about a roller wheel axis and which hasrollers that are mounted on the roller wheel. The rollers roll along acircular path having a certain radius with respect to the roller wheelaxis. The peristaltic hose pump also comprises a pressure arched elementwith a supporting surface, whereby the supporting surface extends alonga circular path having a certain radius around the rotation axis of theroller wheel. In addition, a flexible hose can be inserted between thesupporting surface and the rollers of the roller wheel.

STATE OF THE ART

[0002] A peristaltic hose pump of the aforementioned design is knownfrom DE-G 83 29 579. Here the pressure arched element is formed by adeformable band, the one end of which is firmly clamped, while its otherend is adjustably held in its axial direction, which facilitates theadaptation to different hose diameters. The band made of a metallicmaterial, plastic or fabric has the disadvantage of too high elasticity.Furthermore, the elastic band is stretched over the rollers andrespectively runs in a straight fashion between the rollers, so that theliquid swept volume formed within the hose is reduced, so that thevolume transported and thus the delivery rate are relatively low.

[0003] In order to achieve high pressures and delivery rates withperistaltic hose pumps and to obtain an exact pinching of the hosebetween the rollers of the roller wheel and the pressure arched element,a peristaltic hose pump incorporating a rigid pressure arched element isknown from practice. Here precision hoses with small tolerances areused, and the mechanical parts are manufactured and mounted with highprecision. In spite of this, faults occur due to hose tolerances as wellas manufacturing and mounting tolerances in the mechanical parts.Because tolerances cannot be completely excluded, they are compensatedby means of a spring with which the rigid pressure arched element ispressed against the roller wheel, an arrangement which can, for example,be found on arthroscopic pumps made by the firms Stryker, Arthrex andEMS. The disadvantage here is that the spring force is directional andonly provides the hose with a precise impression at that point of theroller that is in the line of the force. At all other points of theroller only a component of the spring force is exerted. Where the forceacts 90° to the roller, this component is equal to zero. This leads toan only limited compensation for tolerance. It is not possible togenerate high pressures for high delivery rates.

TECHNICAL OBJECTS OF THE INVENTION

[0004] The technical object of the invention is thus to provide aperistaltic pump that has an improved delivery pressure and, inparticular, that thus also provides an improved delivery rate.

BASIS OF THE INVENTION AND PREFERRED EMBODIMENTS

[0005] To solve this problem, the invention provides that the supportingsurface is made of an elastically deformable synthetic material, and thepressure arched element is pre-shaped with the provision that theextension of the supporting surface, when the pressure arched element isnot under tension, essentially corresponds to the extension of thesupporting surface when under tension. This ensures that the hose isclasped between the roller and the pressure arched element by the samecontinuous amount in each position of the roller with respect to thepressure arched element. During the circulating movement of the rollerwheel, the elastic deformation (prestress) runs with the roller throughthe pressure arched element, so that the clasping force always actsperpendicular to the roller. This facilitates compensation for greatertolerances in the hose, production and assembly, which results inconsiderable cost savings in manufacturing the hose pump. Depending onthe respective design of the elastically deformable supporting surfaceof the pressure arched element, the pressures and delivery rate can beincreased by at least 50% as compared with a rigid pressure archedelement. Delivery rates of more than 2 1/min up to 3 1/min can beaccomplished. The unstressed condition corresponds to a mountingposition of the pressure arched element in which a hose can be inserted.The stressed condition corresponds to an operating position in which thesupporting surface is moved in directions towards the rotation axis ofthe roller wheel relative to the mounting position, whereby the hose isclasped between the roller rollers and the supporting surface. Thepressure arched element is mounted or fixed in the region of its twoends, but other than that it is free, i.e. it is not supported by anyother components.

[0006] In the state of the art according to DE-G 83 29 579, the elasticband is tensioned over the rollers and runs straight between therollers, so that the liquid delivery volume within the flexible hose isreduced, so that the volume transported and thus the delivery rate arerelatively small. On the other hand, the rigid pressure arched element,which is pressed against the roller wheel by spring action, only pressesthe hose exactly in the direction of force of the spring in the rollerposition, so that no high pressures for a high delivery rate aregenerated. In contrast, the hose pump according to the inventionprovides that there is sufficient space between two rollers,respectively to transport the liquid, while at the same time highpressures and high delivery rates can be accomplished. The inventionthus overcomes the disadvantages inherent in the previously known hosepumps.

[0007] In one embodiment the pressure arched element consists of a rigidmetallic material and is provided with the supporting surface made ofthe elastically deformable synthetic material. In a further embodimentthe pressure arched element is wholly made of the elastically deformablesynthetic material. The synthetic material is preferably whitepolyoxymethylene (POM). The pressure arched element is thereby made ofmaterials having high elasticity, and can be engineered in such a waythat when it closes due to a prestressed inherent deformation, itpinches the hose on the rollers. When the roller wheel moves, theelastic deformation (prestress) runs through the pressure arched elementwith the roller.

[0008] Further advantageous embodiments of the invention are shown inthe further subclaims. Reference is hereby particularly made to thetensioning device according to subclaim 8. This device tensions thepressure arched element at the same time that the hose pump is closed,so that the operator is not at risk to get his fingers caught betweenthe rollers and the pressure arched element in its stressed condition.

EXAMPLES OF EMBODIMENTS

[0009] The following examples serve to further explain the inventionwith the help of the figures shown. The figures represent the following:

[0010]FIG. 1: perspective representation of the front plate of thedevice housing for two peristaltic hose pumps, without inserted flexiblehoses, whereby the left hose pump is open and the right hose pump isclosed;

[0011]FIG. 2: perspective representation of the front plate according toFIG. 1, without the covers for the two hose pumps;

[0012]FIG. 3: top view of the representation shown in FIG. 2, with aninserted hose;

[0013]FIG. 4: perspective front view of the pressure arched element of ahose pump, and

[0014]FIG. 5: perspective rear view on to the pressure arched elementwith clamping disk.

[0015]FIGS. 1 through 3 show the front plate 15 of a device housing fortwo peristaltic hose pumps 20, 21, whose roller wheels 1 are eachequipped with four rollers 2 and are driven by electric motors 16mounted on the rear side of the front plate 15. Assigned to each rollerwheel 1 with four rollers 2 there is a pressure arched element 3 with asupporting surface 4 on the side facing the rollers 2, whereby thesupporting surface 4 is provided with a run-in zone 5, a middle zone 6and a run-out zone 7, as detailed in FIG. 4. The pressure arched element3 is pivotally mounted on a pivot axis 8 arranged on the front plate 15,while on its opposite end it is provided with a hollow dowel pin 10which on the one hand engages in an adjusting link 25 and, on the otherhand, acts in combination with the snatch posts 26, 27 of a clampingdisk 24, that is rigidly mounted on the front plate 15. Firmly attachedto the adjusting link 25 is a closing plate 13, which can be pivoted bymeans of an actuating element 11 that is attached to it.

[0016] The rollers 2 of the peristaltic hose pumps 20, 21 roll along acircular path having a radius R1 with respect to the rotation axis D ofthe roller wheel 1 along the supporting surface 4 of the pressure archedelement 3, whereby the supporting surface 4 extends along a circularpath having a radius R2 around the rotation axis D of the roller wheel1, and whereby a flexible hose 19 can be inserted between the supportingsurface 4 and the rollers 2 of the roller wheel 1. In the embodimentshown, the pressure arched element 3 and the supporting surface 4 aremade in one piece and of an elastically deformable synthetic material.In another embodiment not shown here, the pressure arched element 3 canalso be made of a metallic material and be provided with an inner-lyinglining made of synthetic material, which then forms the supportingsurface 4. The pressure arched element 3 is preshaped with the provisionthat the extension of the supporting surface 4 when not under tensionessentially corresponds to the extension of the supporting surface 4when under tension.

[0017] The preferred synthetic material used is polyoxymethylene (POM).Preferably Delrin, manufactured by Dupont, or Hostaform, manufactured byHoechst are used. The preferred modulus of elasticity in tension is≧3000 MPa (megapascal). The bending fatigue strength is preferably ≧30MPa. The impact strength at a room temperature of 23° C. is preferably≧130 KJ/m² (kilojoules per square meter). The coefficient of slidingfriction against steel for a dry run is preferably ≧0.30. In tests thatwere conducted, a POM synthetic material with these characteristicsproved particularly suitable for the supporting surface 4 of thepressure arched element 3 of the hose pumps 20, 21.

[0018] Opposing the pressure arched element 4 of each hose pump 20, 21is a bracket 17 firmly mounted on the front plate 15 and having twopassage openings 18 to insert a flexible hose 19 that is respectivelyarranged tangentially to the roller wheel 1 and comes to rest on thesupporting surface 4 on the inner side of the pressure arched element 3.

[0019] The pressure arched element 4 is provided with a run-in zone 5, amiddle zone 6 and a run-out zone 7, whereby the pressure arched element3 has—at least in the run-out zone 7, and preferably also in the run-inzone 5—a larger cross section as compared with the middle zone 6. Withrespect to the rotation axis D of roller wheel 1, the middle zone 6extends across an angle of 10 to 90°, preferably 20 to 60°, with respectto the embracing of the roller wheel 1 by the hose 19. With respect tothe rotation axis D, the pressure arched element 3 extends across anangle of 90 to 180°, preferably 120 to 170°.

[0020] The pressure arched element 3, which is rigidly arranged on thefront plate 15 and mounted on the pivot axis 8 parallel to the rotationaxis D of the roller wheel 1, is, at its other end, pivotally mountedbetween a mounting point I for the hose 19 and an operating point II forthe hose by means of a fixation device 9. For this purpose, the fixationdevice 9 comprises a dowel pin 10 located at the second end of pressurearched element 3, as well as a closing plate 13 with an actuatingelement 11, which is rotatably mounted around a tension rotation axis Srunning parallel to the rotation axis D of the roller wheel 1. Whenswinging the closing plate 13 over from the mounting position I of thehose 19 (in FIG. 1, left hose pump 20) into the operating position II(in FIG. 1, right hose pump 21), the dowel pin 10 is moved from the onesnatch post 26 of the clamping disk 24 to its other snatch post 27,whereby the clamping disk 24 is embodied in a springy manner by anarc-shaped slit 28 running between the two snatch posts 26, 27. In theoperating condition II, the closing plate 13 facially covers the rollerwheel 1 as well as the inserted hose 19, and thus fixes the hose 19 inthe direction of the rotation axis D of the roller wheel 1. In theoperating condition II, the closing plate 13 can be positively engagedin place. The roller wheel 1 and/or the pressure arched element 3 areinterchangeable.

[0021] In FIG. 1, radius R1 to the hose pump 20 is defined as therolling radius of the outside of each roller 2 with respect to therotation axis D of the roller wheel 1, and radius R2 is defined as thedistance between the supporting surface 4 from the middle axis D of theroller wheel 1. With respect to their radial difference R2−R1, theroller wheel 1 and/or the pressure arched element 3 can be selected withthe stipulation that a prescribed hose with a wall thickness of <R2−R1/2is usable.

[0022] The peristaltic hose pumps 20, 21 shown, form an arthroscopicpump in which the hose pump 20 shown on the left in FIG. 1 forms thesuction side, and the hose pump 21 shown on the right in FIG. 1 formsthe flushing side. The hose pump 20 on the suction side rotatesclockwise while the hose pump 21 on the flushing side rotates counterclockwise. Mounts 22 for the hose 19 are provided for both hose pumps20, 21. The mounts 22 incorporate pressure sensors. Between both hosepumps 20, 21, the front plate 15 has a window 23 for a display showingthe values for pressure, delivery rate and similar functions of thearthroscopic pump.

[0023] In an alternative embodiment the pressure arched element 3 has,at least in the middle zone 6, a slit-formed recess that extends along acircular path around the rotation axis D of the roller wheel 1.

1. Peristaltic hose pump comprising a roller wheel (1) which can rotateabout a roller wheel axis D and which has rollers (2) that are mountedon the roller (1), whereby the rollers (2) roll along a circular pathhaving a radius R1 with respect to the roller wheel axis D, and with apressure arched element (3) with a supporting surface (4), whereby thesupporting surface (4) extends along a circular path having a radius R2around the rotation axis D of the roller wheel (1), and whereby aflexible hose (19) can be inserted between the supporting surface (4)and the rollers (2) of the roller wheel (1), characterized by, that thesupporting surface (4) is made of an elastically deformable syntheticmaterial, and that the pressure arched element (3) is pre-shaped withthe provision that the extension of the supporting surface (4), when thepressure arched element (3) is not under tension, essentiallycorresponds to the extension of the supporting surface (4) when undertension.
 2. Peristaltic hose pump according to claim 1, characterizedby, that the pressure arched element (3) is made of an elasticallydeformable synthetic material.
 3. Peristaltic hose pump according toclaims 1 or 2, characterized by, that the synthetic material ispolyoxymethylene (POM).
 4. Peristaltic hose pump according to one ofclaims 1 through 3, characterized by, that the synthetic material has amodulus of elasticity in tension of ≧1000 MPa, preferably ≧3000 MPa(megapascal), a bending fatigue strength of ≧10 MPa, preferably ≧30 MPa,and an impact strength at a room temperature of 23° C. of ≧70 KJ/m²,preferably ≧130 KJ/m² (kilojoules per square meter).
 5. Peristaltic hosepump according to one of claims 1 through 4, characterized by, that thepressure arched element (3) has a run-in zone (5), a middle zone (6) anda run-out zone (7), whereby at least the run-out zone (7), andpreferably also the run-in zone (5) has a larger cross section ascompared with the middle zone (6), preferably an increased thickness indirections orthogonal to the supporting surface.
 6. Peristaltic hosepump according to one of claims 1 through 5, characterized by, that themiddle zone (6) extends across an angle of 10° to 90°, preferably 20° to60° with respect to the roller wheel axis D.
 7. Peristaltic hose pumpaccording to one of claims 1 through 6, characterized by, that, withrespect to the to the rotation axis D, the pressure arched element (3)extends across an angle of 90° to 180°, preferably 120° to 170°. 8.Peristaltic hose pump according to one of claims 1 through 7,characterized by, that the pressure arched element (3) is at its firstend mounted on a pivot axis (8) rigidly arranged on the hose pump (20,21) and running parallel to the rotation axis (D) of the roller wheel(1), and at its second end by means of a fixation device (9) so that itcan pivot between a hose mounting point and an operating point. 9.Peristaltic hose pump according to one of claims 1 through 8,characterized by, that the fixation device (9) comprises a dowel pin(10) located at the second end of the pressure arched element (3) aswell as a closing plate (13), which is rotatably mounted around atension rotation axis S running parallel to the rotation axis (D) of theroller wheel (1), whereby the closing plate (13) interacts with thedowel pin (10) with the provision that when the closing plate (13) isturned from the hose mounting position (I) to the operating position(II), the dowel pin (10) leaves a first snatch post (26) and is pressedinto the second catch post (27) of a clamping disk (24).
 10. Peristaltichose pump according to one of claims 1 through 9, characterized by,that, in the operating position (II), the closing plate (13) faciallycovers the roller wheel (1) as well as the hose (19) placed around it,preferably in such a way that the hose (19) is fixed in the direction ofthe rotation axis (D) of the roller wheel (1).
 11. Peristaltic hose pumpaccording to one of claims 1 through 10, characterized by, that, in theoperating position (II), the closing plate (13) can be positivelyengaged in place.
 12. Peristaltic hose pump according to one of claims 1through 11, characterized by, that the roller wheel (1) and/or thepressure arched element (3) are interchangeable.
 13. Peristaltic hosepump according to one of claims 1 through 12, characterized by, that,with respect to their radial difference R2−R1, the roller wheel (1)and/or the pressure arched element (3) can be selected with thestipulation that in mounting position (I) a prescribed hose (19) with anouter diameter of less than R2−R1 can be inserted.
 14. Peristaltic hosepump according to one of claims 1 through 13, characterized by, that,with respect to their radial difference R2−R1, the roller wheel (1)and/or the pressure arched element (3) can be selected with thestipulation that a prescribed hose (19) with a wall thickness of<(R2−R1)/2 can be inserted.